The function of this core is not changed from the original grant. Basically, this core is designed to perform necessary laboratory tests for the routine phenotyping of the hematopoietic cells from CML patients in chronic phase and blast crisis who are entered on the therapeutic protocols and laboratory analysis listed in Figures 1-2 and Table I. These include light morphology, ultrastructure, Southern blots for bcr rearrangement, immunophenotype, and cytogenetics to establish the diagnosis of CML. Support is requested only for cytogenetic analyses required for the evaluation of the percentage of Philadelphia-chromosome positive (Ph+) cells in the bone marrow, pheresed peripheral blood, or CD34+ selected cells of patients following therapy (Project 1A-D). The cytogenetic assays used will include not only the classical G-banding method but also the newly-developed fluorescent in situ hybridization (FISH) method that detects the 9;22 chromosomal translocation by using chromosome-specific DNA probes. Our preliminary studies demonstrated that the FISH method could be effectively used to detect the 9;22 translocation in poorly-spread metaphases and in interphase nuclei that were otherwise unanalyzable by the routine cytogenetic methods. Therefore, the inclusion of the use of FISH in the Core should significantly improve our ability to evaluate the effectiveness of therapy and the strategies for collecting normal diploid progenitor cells for autografts. This Core should also allow us to compare FISH with cytogenetics to determine if the former is better than the latter for detecting minimal residual disease in CML and for predicting relapse. The Results of cytogenetic and FISH analyses will also be correlated with results from other assays in Projects II-VI.